This example uses the Palmer Penguins data set: https://github.com/allisonhorst/palmerpenguins.
library(palmerpenguins) # penguin data
library(pander) # nicely formatted tables
pander(head(penguins)) # nicely formatted table of top of data
| species | island | bill_length_mm | bill_depth_mm | flipper_length_mm |
|---|---|---|---|---|
| Adelie | Torgersen | 39.1 | 18.7 | 181 |
| Adelie | Torgersen | 39.5 | 17.4 | 186 |
| Adelie | Torgersen | 40.3 | 18 | 195 |
| Adelie | Torgersen | NA | NA | NA |
| Adelie | Torgersen | 36.7 | 19.3 | 193 |
| Adelie | Torgersen | 39.3 | 20.6 | 190 |
| body_mass_g | sex | year |
|---|---|---|
| 3750 | male | 2007 |
| 3800 | female | 2007 |
| 3250 | female | 2007 |
| NA | NA | 2007 |
| 3450 | female | 2007 |
| 3650 | male | 2007 |
We calculate the correlation of body mass and flipper length.
We need to use the option
use = "complete.obs"to avoid an error message because some observations have missing data.
cor(penguins$body_mass_g,
penguins$flipper_length_mm,
use = "complete.obs")
[1] 0.8712018
There is some indication that penguins with higher body mass have longer flippers.
To get a more nicely formatted correlation value, we can read this correlation into a variable, and then print out this correlation as part of a sentence in inline code. See this RMarkdown document for how this is done, or take a look at this page from RStudio.
mycorrelation <- cor(penguins$body_mass_g,
penguins$flipper_length_mm,
use = "complete.obs")
The value of the correlation is 0.8712018.
plot(penguins$body_mass_g,
penguins$flipper_length_mm)
plot(penguins$body_mass_g,
penguins$flipper_length_mm,
col = "blue",
pch = 19, # Plotting CHaracter
xlab = "body mass",
ylab = "flipper length",
main = "Penguin Body Mass and Flipper Length")
library(ggplot2)
ggplot(penguins,
aes(x = body_mass_g,
y = flipper_length_mm)) +
geom_point() +
geom_smooth() +
labs(title = "Penguin Body Mass and Flipper Length",
x = "body mass",
y = "flipper length")
Gorman KB, Williams TD, Fraser WR (2014). Ecological Sexual Dimorphism and Environmental Variability within a Community of Antarctic Penguins (Genus Pygoscelis). PLoS ONE 9(3): e90081. https://doi.org/10.1371/journal.pone.009008